Insulin on Muscle

Question 1

What are the types of glucose transporter?

Answer 1

SGLT

GLUTs

Question 2

How many TM domains does the SGLT have?

Answer 2

14

Question 3

What part of the SGLT binds the sugar?

Answer 3

C-terminus

Question 4

How does the SGLT work?

Answer 4

Na binds a negative charge in the transporter, opens up for glucose, glucose binds causing conformational change and the release of glucose and Na on the other side

Question 5

What are the transporters on the basolateral membrane of the gut?

Answer 5

Na-K ATPase

GLUT2

Question 6

What are the features of GLUTs?

Answer 6

present on the surface of all cell membranes
transport glucose down a concentration gradient
energy dependent process
can operate bi-directionally as long as down the gradient

Question 7

What are the classes of GLUTs?

Answer 7

Class I
Class II
Class III

Question 8

What are the features of the gluts in class I?

Answer 8

1,3,4 are all high affinity
2 is low affinity
they all transport glucose

Question 9

What are the features of the gluts in class II?

Answer 9

5,7,9,11 and HMIT1

low affinity for glucose, transport fructose

Question 10

What are the features of the gluts in class III?

Answer 10

6,8,10,12

not really sure yet

Question 11

How many TM domains do GLUTs have?

Answer 11

12

Question 12

Where is GLUT1 generally found?

Answer 12

ubiquitously

Question 13

Where is GLUT2 generally found?

Answer 13

kidney, sm. intesting, liver, pancreatic b cells

Question 14

Where is GLUT 3 found?

Answer 14

neurons and placenta

Question 15

Where is GLUT 4 found?

Answer 15

skeletal muscle, cardiac muscle, adipose tissue

Question 16

Where is GLUT 4 found?

Answer 16

skeletal muscle, cardiac muscle, adipose tissue

Question 17

What is GLUT4 responsible for?

Answer 17

the response to insulin

Question 18

What is cytochalasin B?

Answer 18

a fungal metabolite called CB which binds to GLUTs in a non-competitive manner

Question 19

What is useful about CB?

Answer 19

It gives you a 1:1 molar ratio to the number of transporters present

Question 20

What can be observed with insulin treatment?

Answer 20

translocation of transporters from the Intracellular membrane to the plasma membrane

Question 21

How can the translocating transporter be identified?

Answer 21

with antibodies and GFP

Question 22

Why is this finding important?

Answer 22

muscle is the principal tissue for glucose use in the fed state
muscle is a primary target of insulin
muscle must be fully responsive to insulin in order to lower blood glucose

Question 23

What does phosphorylation of the insulin receptor cause?

Answer 23

phosphorylation of docking proteins such as IRS-1,2,3,4

Question 24

What does phosphorylation of docking proteins cause?

Answer 24

activation of signalling pathways PI3K, PKB, MAPK, p70S6

Question 25

What does activation of the signalling pathways cause?

Answer 25

glucose transport, glycogen synthesis, lipogenesis, protein synthesis, gene expression, cellular growth

Question 26

What does Insulin cause in muscle?

Answer 26

increase glucose up take
increase glucose use -> glycogen and glycolysis
increase amino acid uptake
increase protein synthesis, decreased protein breakdown

Question 27

What is the skeletal muscle glucose uptake during exercise regulated by?

Answer 27

glucose supply, glucose transport

glucose phosphorylation

Question 28

How does glucose phosphorylation maintain the concentration gradient?

Answer 28

It cannot exit the cell, so glucose can keep coming in

Question 29

How does exercise simulate the effects of insulin?

Answer 29

increases the translocation of GLUT 4 via AMPK

Question 30

What does Metformin do?

Answer 30

suppresses hepatic glucose production
increases muscle glucose uptake
inhibits complex 1 of respiratory chain

Question 31

What shares the metabolic effect of Metformin?

Answer 31

AICAR